| Popis: |
In this paper, we solve the following bi-additive $s$-functional inequality $\begin{array}{*{20}{c}}\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;{\left\| {f(x - y,y + z) + f\left( {y + z,z - x} \right) + f\left( {z + x,x - z} \right) - f\left( {x - y,x + y} \right)\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\left( {0.1} \right)} \right.}\\\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;{ \le \left\| {s\left( {f\left( {y - z,z + x} \right) + f\left( {z + x,x - y} \right) + f\left( {x + y,y - x} \right) - f\left( {y - z,y + z} \right)} \right)} \right\|,}\end{array}$ where $s$ is a fixed nonzero complex number satisfying $|s| |
